Method for forming three-dimensional integrated wiring structure and semiconductor structure thereof

ABSTRACT

Embodiments of methods and structures for forming a 3D integrated wiring structure are disclosed. The method can include forming an insulating layer on a front side of a first substrate; forming a semiconductor layer on a front side of the insulating layer; patterning the semiconductor layer to expose at least a portion of a surface of the insulating layer; forming a plurality of semiconductor structures over the front side of the first substrate, wherein the semiconductor structures include a plurality of conductive contacts and a first conductive layer; joining a second substrate with the semiconductor structures; performing a thinning process on a backside of the first substrate to expose the insulating layer and one end of the plurality of conductive contacts; and forming a conductive wiring layer on the exposed insulating layer.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. Non-Provisional patentapplication Ser. No. 16/996,022 filed on Aug. 18, 2020 and titled“Method For Forming Three-Dimensional Integrated Wiring Structure AndSemiconductor Structure Thereof,” which is a continuation of U.S.Non-Provisional patent application Ser. No. 16/868,160 filed on May 6,2020 and titled “Method For Forming Three-Dimensional Integrated WiringStructure And Semiconductor Structure Thereof,” which claims priority toU.S. Non-Provisional patent application Ser. No. 16/046,899 filed onJul. 26, 2018, which claims priority to Chinese Patent Application No.201710775896.4 filed on Aug. 31, 2017 and PCT Application No.PCT/CN2018/090475 filed on June 8, 2018. The entire contents of theseapplications are incorporated herein by reference.

BACKGROUND

Embodiments of the present disclosure relate to the field ofsemiconductor manufacturing technology, and in particular to method forforming a three-dimensional (3D) integrated wiring structure (e.g., amemory structure.)

Planar memory cells are scaled to smaller sizes by improving processtechnology, circuit design, programming algorithm, and fabricationprocess. However, as feature sizes of the memory cells approach a lowerlimit, planar process and fabrication techniques become challenging andcostly. As a result, memory density for planar memory cells approachesan upper limit.

A 3D memory architecture can address the density limitation in planarmemory cells. The 3D memory architecture includes a memory array andperipheral devices for controlling signals to and from the memory array.

BRIEF SUMMARY

Embodiments of methods for forming a three-dimensional (3D) integratedwiring structure and semiconductor structures thereof are disclosedherein.

Disclosed is a method for forming a 3D integrated wiring structure,including: forming an insulating layer on a front side of a firstsubstrate; forming a semiconductor layer on a front side of theinsulating layer; patterning the semiconductor layer to expose at leasta portion of a surface of the insulating layer; forming a plurality ofsemiconductor structures over the front side of the first substrate,wherein the semiconductor structures include a plurality of conductivecontacts and a first conductive layer; joining a second substrate withthe semiconductor structures; performing a thinning process on abackside of the first substrate to expose the insulating layer and oneend of the plurality of conductive contacts; and forming a conductivewiring layer on the exposed insulating layer.

In some embodiments, the plurality of conductive contacts penetrates atleast a portion of the semiconductor structures and the insulating layerin a vertical direction. In some embodiments, the plurality ofconductive contacts connects to the conductive wiring layer at one endand connects to the first conductive layer at the other end.

In some embodiments, the method further includes forming a wiringpattern by etching the conductive wiring layer, and the wiring patternis electrically connected to the plurality of conductive contacts.

In some embodiments, the method further includes disposing a passivationlayer over the conductive wiring layer and the exposed insulating layer.In some embodiments, the disposing of a passivation layer includeslithography and etching.

In some embodiments, forming the semiconductor layer includes disposingpolycrystalline silicon, or single crystalline silicon on a front sideof the insulating layer.

In some embodiments, joining a second substrate with the semiconductorstructures includes a bonding process including adhesive bonding, anodicbonding, direct wafer bonding, eutectic bonding, hybrid metal/dielectricbonding, or a combination thereof.

In some embodiments, forming the plurality of semiconductor structuresincludes forming a plurality of 3D memory structures. In someembodiments, forming the plurality of 3D memory structures includesforming a memory device layer, a first conductive layer, and a pluralityof conductive contacts within the memory device layer connecting to thefront side of the first substrate at one end and connecting to the firstconductive layer at the other end.

In some embodiments, forming the plurality of 3D memory structuresincludes forming a plurality of stacked memory cells.

Another aspect of the present disclosure provides a structure,including: an insulating layer; a patterned semiconductor layer disposedon a front side of the insulating layer; a plurality of semiconductorstructures formed on at least a portion of the patterned semiconductorlayer and the insulating layer, wherein the plurality of semiconductorstructures includes a plurality of conductive contacts and a firstconductive layer; and a conductive wiring layer disposed on a backsideof the insulating layer.

In some embodiments, the structure further includes a first substrate onthe backside of the insulating layer. In some embodiment, at least aportion of the first substrate includes a reduced thickness. In someembodiments, at least a portion of the first substrate is removed toexpose at least a portion of the backside of the insulating layer.

In some embodiments, the structure further includes a second substratejoined to a front side of the plurality of semiconductor structures.

In some embodiments, the plurality of conductive contacts connects tothe conductive wiring layer at one end and connects to the firstconductive layer at the other end.

In some embodiments, the structure further includes a passivation layerdisposed on the conductive wiring layer and the exposed insulatinglayer.

In some embodiments, a thickness of the insulating layer is betweenabout 0.3 μm and 5 μm.

In some embodiments, the patterned semiconductor layer includes singlecrystalline silicon, or polycrystalline silicon.

In some embodiments, a thickness of the patterned semiconductor layer isbetween about 0.03 μm and 1 μm.

In some embodiments, the plurality of conductive contacts and conductivewiring layer include copper, silver, aluminum, tin, tungsten, or acombination thereof

In some embodiments, a diameter of the conductive contact is betweenabout 0.3 μm and 5 μm.

In some embodiments, the plurality of semiconductor structures includesa plurality of 3D memory structures.

In some embodiments, the plurality of 3D memory structures includes amemory device layer having a plurality of stacked memory cells, aplurality of conductive contacts, and a first conductive layer. In someembodiments, the plurality of conductive contacts connects to theconductive wiring layer at one end and connects to the first conductivelayer at the other end.

In some embodiments, a thickness of the 3D memory device structure isbetween about 1 μm and 50 μm.

Other aspects of the present disclosure can be understood by thoseskilled in the art in light of the description, the claims, and thedrawings of the present disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated herein and form a partof the specification, illustrate embodiments of the present disclosureand, together with the description, further serve to explain theprinciples of the present disclosure and to enable a person skilled inthe pertinent art to make and use the present disclosure.

FIG. 1 illustrates a wiring method.

FIG. 2 illustrates a wiring method for forming a 3D semiconductorstructure.

FIG. 3 is a flowchart of an exemplary wiring method for forming a 3Dintegrated wiring structure, according to some embodiments of thepresent disclosure.

FIGS. 4-9 illustrate an exemplary fabrication process for forming a 3Dintegrated wiring structure, according to some embodiments of thepresent disclosure.

Embodiments of the present disclosure will be described with referenceto the accompanying drawings.

DETAILED DESCRIPTION

Although specific configurations and arrangements are discussed, itshould be understood that this is done for illustrative purposes only. Aperson skilled in the pertinent art will recognize that otherconfigurations and arrangements can be used without departing from thespirit and scope of the present disclosure. It will be apparent to aperson skilled in the pertinent art that the present disclosure can alsobe employed in a variety of other applications.

It is noted that references in the specification to “one embodiment,”“an embodiment,” “an example embodiment,” “some embodiments,” etc.,indicate that the embodiment described may include a particular feature,structure, or characteristic, but every embodiment may not necessarilyinclude the particular feature, structure, or characteristic. Moreover,such phrases do not necessarily refer to the same embodiment. Further,when a particular feature, structure or characteristic is described inconnection with an embodiment, it would be within the knowledge of aperson skilled in the pertinent art to effect such feature, structure orcharacteristic in connection with other embodiments whether or notexplicitly described.

In general, terminology may be understood at least in part from usage incontext. For example, the term “one or more” as used herein, dependingat least in part upon context, may be used to describe any feature,structure, or characteristic in a singular sense or may be used todescribe combinations of features, structures or characteristics in aplural sense. Similarly, terms, such as “a,” “an,” or “the,” again, maybe understood to convey a singular usage or to convey a plural usage,depending at least in part upon context. In addition, the term “basedon” may be understood as not necessarily intended to convey an exclusiveset of factors and may, instead, allow for existence of additionalfactors not necessarily expressly described, again, depending at leastin part on context.

It should be readily understood that the meaning of “on,” “above,” and“over” in the present disclosure should be interpreted in the broadestmanner such that “on” not only means “directly on” something but alsoincludes the meaning of “on” something with an intermediate feature or alayer therebetween, and that “above” or “over” not only means themeaning of “above” or “over” something but can also include the meaningit is “above” or “over” something with no intermediate feature or layertherebetween (i.e., directly on something).

Further, spatially relative terms, such as “beneath,” “below,” “lower,”“above,” “upper,” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement(s) or feature(s) as illustrated in the figures. The spatiallyrelative terms are intended to encompass different orientations of thedevice in use or operation in addition to the orientation depicted inthe figures. The apparatus may be otherwise oriented (rotated 90 degreesor at other orientations) and the spatially relative descriptors usedherein may likewise be interpreted accordingly.

As used herein, the term “substrate” refers to a material onto whichsubsequent material layers are added. The substrate itself can bepatterned. Materials added on top of the substrate can be patterned orcan remain unpatterned. Furthermore, the substrate can include a widearray of semiconductor materials, such as silicon, germanium, galliumarsenide, indium phosphide, etc. Alternatively, the substrate can bemade from an electrically non-conductive material, such as a glass, aplastic, or a sapphire wafer.

As used herein, the term “layer” refers to a material portion includinga region with a thickness. A layer can extend over the entirety of anunderlying or overlying structure, or may have an extent less than theextent of an underlying or overlying structure. Further, a layer can bea region of a homogeneous or inhomogeneous continuous structure that hasa thickness less than the thickness of the continuous structure. Forexample, a layer can be located between any pair of horizontal planesbetween, or at, a top surface and a bottom surface of the continuousstructure. A layer can extend horizontally, vertically, and/or along atapered surface. A substrate can be a layer, can include one or morelayers therein, and/or can have one or more layer thereupon, thereabove,and/or therebelow. A layer can include multiple layers. For example, aninterconnect layer can include one or more conductor and contact layers(in which contacts, interconnect lines, and/or vias are formed) and oneor more dielectric layers.

As used herein, the term “contact” can broadly include any suitabletypes of interconnects, such as middle-end-of-line (MEOL) interconnectsand back-end-of-line (BEOL) interconnects, including verticalinterconnect accesses (e.g., vias) and lateral lines (e.g., interconnectlines).

As used herein, the term “nominal/nominally” refers to a desired, ortarget, value of a characteristic or parameter for a component or aprocess operation, set during the design phase of a product or aprocess, together with a range of values above and/or below the desiredvalue. The range of values can be due to slight variations inmanufacturing processes or tolerances. As used herein, the term “about”indicates the value of a given quantity that can vary based on aparticular technology node associated with the subject semiconductordevice. Based on the particular technology node, the term “about” canindicate a value of a given quantity that varies within, for example,10-30% of the value (e.g., ±10%, ±20%, or ±30% of the value).

As used herein, the term “vertical/vertically” means nominallyperpendicular to a lateral surface of a substrate.

As used herein, the term “3D memory device” refers to a semiconductordevice with vertically-oriented strings of memory cell transistors(referred to herein as “memory strings,” such as NAND strings) on alaterally-oriented substrate so that the memory strings extend in thevertical direction with respect to the substrate.

As shown in FIG. 1, current wafer wiring technology includes etchingdirectly from the backside of a wafer 101, exposing a first conductivelayer (M₁) 110 and forming an electrical connection between a conductivewiring layer 126 and the first conductive layer 110 through vias 108. Asshown in FIG. 2, in current three dimensional (3D) memory technology,the memory cell is fabricated perpendicularly to the wafer surface,forming a thick semiconductor device layer 208 with a thickness up toabout 5 microns (μm), between a conductive wiring layer 226 and a firstconductive layer 210, which makes forming an electrical contact betweenthe conductive wiring layer 226 and the first conductive layer 210challenging using traditional wiring techniques.

Various embodiments in accordance with the present disclosure provide amethod for forming a 3D integration wiring structure and a semiconductordevice with an interconnect structure. The method for forming a 3Dintegrated wiring structure disclosed herein can include forming aninsulating layer on a front side of a first substrate; forming asemiconductor layer on a front side of the insulating layer; patterningthe semiconductor layer to expose at least a portion of a surface of theinsulating layer; forming a plurality of semiconductor structures,including a plurality of conductive contacts and a first conductivelayer, over the front side of the first substrate; joining a secondsubstrate with the semiconductor structures; performing a thinningprocess on a backside of the first substrate to expose the insulatinglayer and one end of the plurality of conductive contacts; and forming aconductive wiring layer on the exposed insulating layer. As a result,the method for forming a 3D integrated wiring structure disclosed hereincan provide an interconnect structure and enable wiring through a thicksemiconductor device layer to streamline fabrication process, reduceproduction cost and improve device quality.

FIG. 3 is a flowchart of an exemplary integrated wiring method 300 forforming a 3D memory device, according to some embodiments of the presentdisclosure. FIGS. 4-9 illustrate an exemplary fabrication method to forma 3D memory device, according to some embodiments of the presentdisclosure. It should be understood that the steps shown in method 300and the fabrication method shown in FIGS. 4-9 are not exhaustive andthat other methods and steps can be performed as well before, after, orbetween any of the illustrated methods and steps.

Referring to FIG. 3 and FIG. 4, method 300 starts at step 302, in whichan insulating layer 404 is formed on a front side 403 of a firstsubstrate 402 and a semiconductor layer 412 is formed on a front side407 of the insulating layer 404. As used herein, the term “front side”of a structure refers to the side of the structure at which a device isformed. Conversely, as used herein, the term “backside” refers to theside of the structure that is opposite to the front side. For ease ofillustration, structures of the first substrate 402, the insulatinglayer 404, and the semiconductor layer 412 are shown upside down suchthat a backside 405 of the first substrate 402 is above a front side 403of the first substrate 402; the backside 409 of the insulating layer 404is above a front side 407 of the insulating layer 404; and the backside413 of the semiconductor layer 412 is above the front side 411 of thesemiconductor layer 412. It is worth to note that the backside 409 ofthe insulating layer 404 merges with the front side 403 of the firstsubstrate 402 and the backside 413 of the semiconductor layer 412 mergeswith the front side 407 of the insulating layer 404.

The materials of the first substrate 402 or the semiconductor layer 412can include silicon, germanium, a III-V semiconductor, silicon carbide,silicon on insulating substrate, or a combination thereof. In someembodiments, the first substrate 402 can include silicon (e.g.,monocrystalline silicon, polycrystalline silicon), silicon germanium(SiGe), gallium arsenide (GaAs), germanium (Ge), silicon on insulator(SOI), germanium on insulator (GOI), or any suitable combinationthereof. In some embodiments, the first substrate 402 is a siliconwafer. In some embodiments, the semiconductor layer 412 comprisespolycrystalline silicon or single crystalline silicon, or a combinationthereof. The method for forming the semiconductor layer 412 comprisesone or more thin film deposition processes, such as ALD (Atomic LayerDeposition), CVD (Chemical Vapor Deposition), LPCVD (Low pressurechemical vapor deposition), PVD (Physical Vapor Deposition), or acombination thereof.

An exemplary fabrication method to form the insulating layer 404 by CVDis disclosed as follows. The CVD is performed at a deposition pressureof 1600-1700 mtorr, flux of ammonia and/or oxygen of 5000-8000 sccm,flux of SiH₄ of 800-1500 mtorr, RF power of 5500-7500 watt, anddeposition temperature of 450-500° C.

An exemplary fabrication method to form the insulating layer 404 bythermal oxidation is disclosed as follows. Thermal oxidation process caninclude dry oxidation or wet oxidation, wherein the dry oxidation isperformed at oxygen flux of 0.29-1.55 L/min, nitrogen flux of 2-18L/min, pressure of 0.51-1.51 atm, temperature of 710-790° C., and thewet oxidation is performed at water vapor flux of 0.11-0.99 L/min,nitrogen flux of 1.5-18.5 L/min, pressure of 0.55-1.4 atm, andtemperature of 720-750° C.

An exemplary fabrication method to form the semiconductor layer 412comprising polycrystalline silicon by LPCVD is disclosed as follows. Insome embodiments, the LPCVD is performed with a reaction gas of SiH₄,chamber temperature of 710-740° C., chamber pressure of 255-345 mtorr,SiH₄ flux of 110-190 sccm. The reaction gas can further include a buffergas comprising Ar and the flux of the Ar gas is 5.1-19 L/min. In someembodiments, the LPCVD is performed with a reaction gas of SiH₄, chambertemperature of 610-640° C., chamber pressure of 251-345 mtorr, SiH₄ fluxof 110-199 sccm. The reaction gas can further include a buffer gascomprising Ar and the flux of the Ar gas is 5.5-18 L/min. In someembodiments, the LPCVD is performed with a reaction gas of SiH₄, chambertemperature of 690-710° C., chamber pressure of 460-540 mtorr, SiH₄ fluxof 145-235 sccm. The reaction gas can further include a buffer gascomprising Ar and the flux of the Ar gas is 11-29 L/min. In someembodiments, the LPCVD is performed with a reaction gas of SiH₄, chambertemperature of 650-680° C., chamber pressure of 450-550 mtorr, SiH₄ fluxof 150-250 sccm. The reaction gas can further include a buffer gascomprising Ar and the flux of the Ar gas is 15-20 L/min.

In some embodiments, the thickness of the semiconductor layer 412 isbetween about 0.03 μm and 1 μm. In some embodiments, the thickness ofthe semiconductor layer 412 is between about 0.03 μm and 0.1 μm. In someembodiments, the thickness of the semiconductor layer 412 is betweenabout 0.05 μm and 1 μm.

In some embodiments, the material for the insulating layer 404 caninclude oxides, nitrides, oxynitrides or a combination thereof. In someembodiments, the method for forming the insulating layer 404 comprisesthermal oxidation, thermal nitridation, thermal oxynitridation, CVD,PVD, or a combination thereof. In some embodiments, the method forforming the insulating layer further comprises planarizing or flatteninga surface of the insulating layer 404 via Chemical Mechanical Polishing(CMP).

In some embodiments, the thickness of the insulating layer is between0.3 μm and 5 μm. In some embodiments, the thickness of the insulatinglayer is between 0.3 μm and 1 μm. In some embodiments, the thickness ofthe insulating layer is between 0.1 μm and 3 μm. In some embodiments,the thickness of the insulating layer is about 1 μm.

Referring to FIG. 3, method 300 proceed to step 304, in which thesemiconductor layer is patterned. As illustrated in FIG. 5, a method toform the patterned semiconductor layer 512 includes, but not limited to,lithography, etching, deposition, polishing, CMP or a combinationthereof. In some embodiments, a dielectric layer covers thesemiconductor layer 412 (shown in FIG. 4) and a front side 407 of theinsulating layer 404 followed by exposing a front side 411 of thesemiconductor layer 412 through deposition, etching or optionally CMP toform to form the patterned semiconductor layer 512.

Referring to FIG. 3 and FIG. 6, method 300 proceeds to step 306, inwhich a plurality of semiconductor structures 620 is formed at the frontside 407 of the insulating layer 404, over the front side of the firstsubstrate. As illustrated in FIG. 6, a plurality of semiconductorstructures 620 can include the patterned semiconductor layer 512, asemiconductor device layer 608 at the front side 407 of the insulatinglayer 404, a plurality of conductive contacts 606 (through arraycontacts (TACs) or contact vias) formed within the semiconductor devicelayer 608, and a first conductive layer 610 (M₁). The insulating layer404 is between the front side 403 of the first substrate 402 and thesemiconductor structure 620. As used herein, the term “front side” of astructure refers to the side of the structure at which a semiconductorstructure is formed. In some embodiments, the conductive contacts 606extend vertically into the insulating layer 404. In some embodiments,the conductive contacts 606 extend vertically into the semiconductorlayer 404 and contact to the front side of the first substrate. In someembodiments, the length of the conductive contacts 606 ranges from about0.5 μm to 5 μm. In some embodiments, the length of the conductivecontacts 606 ranges from about 0.5 μm to 1 μm. In some embodiments, thediameter of the conductive contacts 606 is between about 0.3 μm and 5μm. In some embodiments, the diameter of the conductive contacts 606 isbetween about 0.3 μm and 1 μm. In some embodiments, the thickness ofpatterned semiconductor layer 512 is between about 0.03 μm and 1 μm.

In some embodiments, the semiconductor structure 620 is a memory arraystructure. In some embodiments, the semiconductor structure is a 3Dmemory structure. In some embodiments, the semiconductor device layer608 can include a memory stack. In some embodiments, the semiconductordevice layer 608 is a memory device layer. In some embodiments, thememory stack is formed by repeatedly stacking a plurality of memorycells. In some embodiments, the thickness of the semiconductor devicelayer 608 is between about 1 μm and 50 μm. In some embodiments, thethickness of the semiconductor device layer 608 is between about 1 μmand 10 μm. In some embodiments, the thickness of the semiconductordevice layer 608 is between about 5 μm and 50 μm. In some embodiments,the thickness of the semiconductor device layer 608 is about 5 μm. Insome embodiments, the thickness of the semiconductor device layer 608 isgreater than 5 μm.

In some embodiments, memory array stack is formed by multiplefabrication methods, including, but not limited to, thin film depositionof dielectric layers, etching of channel holes and slits, thin filmdeposition of memory films in the channel holes, and gate and word linereplacement. In some embodiments, memory array stack can be formed(e.g., disposed) at the front side 403 of the first substrate 402 andcan include an alternating conductor/dielectric stack and an array ofNAND strings extending through the alternating conductor/dielectricstack. The alternating conductor/dielectric stack can includealternating conductor layers (e.g., metal layers or polysilicon layers)and dielectric layers (e.g., silicon oxide layers or silicon nitridelayers). Each NAND string can include a plurality of vertically-stackedmemory cells each controlled by a respective conductor layer(functioning as a control gate) of the alternating conductor/dielectricstack that surrounds the NAND string. The conductor layers in thealternating conductor/dielectric stack can extend in the lateraldirection outside the memory array region to thereby form word lines ofthe semiconductor structure 620 (e.g., memory array structure). EachNAND string can also include a drain terminal at an end (e.g., at thefront side 615 of the semiconductor structure 620). The drain terminalof each NAND string can be electrically connected to a respective one ofa plurality of bit lines of the semiconductor structure 620. In someembodiments, each NAND string further includes multiple select gates(e.g., a source select gate and a drain select gate). Some structuresdescribed in this paragraph are not shown in FIG. 6 as they would beappreciated by a person skilled in the pertinent art.

The semiconductor structure 620 can include one or more conductivecontacts 606 (TACs or contact vias) each extending vertically through atleast part of the semiconductor structure 620. In some embodiments,conductive contacts 606 can extend vertically through the entirethickness of the semiconductor structure 620. For example, theconductive contacts 606 can pass through the entire thickness of thesemiconductor device layer 608, the entire thickness of the insulatinglayer 404 and part of the entire thickness of the first substrate 402.In some embodiments, the conductive contacts 606 can pass through theentire thickness of the semiconductor device layer 608 and part of theentire thickness of the insulating layer 404. In some embodiments, theconductive contacts 606 can pass through the entire thickness of thesemiconductor device layer 608 and the entire thickness of theinsulating layer 404 so that the conductive contacts 606 reach thebackside 409 of the insulating layer 404. In some embodiments, theconductive contacts 606 can pass through part of the entire thickness ofthe semiconductor device layer 608 without reaching to the firstsubstrate 402. In some embodiments, the conductive contacts 606 is incontact with the first substrate 402 at the side 403, and in contactwith the first conductive layer 610 at the other end. In someembodiments, the conductive contacts penetrate at least a portion of thesemiconductor structures and the insulating layer in a verticaldirection.

Each conductive contact 606 can include a vertical opening filled withconductor materials, including, but not limited to, tungsten (W), cobalt(Co), copper (Cu), aluminum (Al), doped silicon, silicides, a metaloxide (e.g. titanium oxide), a metal nitride (e.g titanium nitride) or acombination thereof.

In some embodiments, the diameter of the conductive contacts is betweenabout 0.3 μm and 5 μm. In some embodiments, the diameter of theconductive contacts is between about 0.3 μm and 1 μm. In someembodiments, the diameter of the conductive contacts is about 1 μm.

The conductive contacts 606 can be in the memory array region and/oroutside the memory array region, for example, in a staircase region ofthe semiconductor structure 620. The conductive contacts 606 can formelectrical connection with word line contacts, bit line contacts, andgate select contacts. The word line contacts can be in the staircaseregion and electrically connect to the word lines, such that each wordline contact can individually address the corresponding word line. Thebit line contacts can electrically connect to the NAND strings by thebit lines, such that each bit line contact can individually address thecorresponding NAND string. The gate select contacts can electricallyconnect to the select gates. Some structures described in this paragraphare not shown in FIG. 6, as they would be appreciated by a personskilled in the pertinent art.

The semiconductor structure 620 can include a first conductive layer 610at the front side of the semiconductor structure 620. The firstconductive layer 610 can provide connection to the memory arraystructure and/or the peripheral device structure. The first conductivelayer 610 can be patterned based on the layout of the internal structureof memory array device and/or the peripheral device structure, so thatsuitable interconnect structures can be formed. The first conductivelayer 610 can include, but not limited to, W, Co, Cu, Al, metalsilicides, or any other suitable materials.

Referring to FIG. 3 and FIG. 7, method 300 proceeds to step 308, inwhich a second substrate 716 is joined to the semiconductor structure620, followed by a thinning process of the first substrate 402. Asillustrated in FIG. 7, a second substrate 716 can be bonded to thesemiconductor structure 620 (with a bonding interface at a front side615) through adhesive bonding, anodic bonding, direct wafer bonding,eutectic bonding, hybrid metal/dielectric bonding or a combinationthereof. Adhesive bonding, also referred to as gluing or glue bonding,is a wafer bonding technique with applying an intermediate layer toconnect substrates of different materials. Anodic bonding is a waferbonding process to seal glass to either silicon or metal withoutintroducing an intermediate layer, which is commonly used to seal glassto silicon wafers in electronics and microfluidics, through electricfields. Direct bonding, also referred to as fusion bonding, is a waferbonding process without any additional intermediate layers. The directbonding process is based on chemical bonds between two surfaces ofmaterial meeting specific requirements. The direct bonding process caninclude wafer preprocessing, pre-bonding at room temperature andannealing at elevated temperatures. Eutectic bonding, also referred toas eutectic soldering, is a wafer bonding technique with an intermediatemetal layer that can produce a eutectic system. Hybrid bonding, alsoknown as “metal/dielectric hybrid bonding,” can be a direct bondingtechnology (e.g., forming bonding between surfaces without usingintermediate layers, such as solder or adhesives), which obtainsmetal-metal bonding and dielectric-dielectric bonding simultaneously.

The materials of the second substrate 716 can be silicon, germanium, aIII-V semiconductor, silicon carbide, glass, plastic film, or silicon oninsulating substrate, or a combination thereof. In some embodiments, thesecond substrate 716 can include silicon (e.g., monocrystalline silicon,polycrystalline silicon), silicon germanium (SiGe), gallium arsenide(GaAs), germanium (Ge), silicon on insulator (SOI), germanium oninsulator (GOI), or any suitable combination thereof. In someembodiments, the second substrate 716 is silicon wafer.

Then the first substrate 402 is thinned from the backside 405 (shown inFIG. 6) through techniques including, but not limited to, mechanicalgrinding (e.g., polishing), chemical mechanical planarization, wetetching and atmospheric downstream plasma dry chemical etching. acombination thereof.

In some embodiments, the thinning process removes the first substrate402. In some embodiments, the thinning process removes at least aportion of the first substrate 402. In some embodiments, the thinningprocess removes the first substrate 402 and reduces the thickness of theinsulating layer 404 from an initial range of about 0.3-5 μm down to afinal range of about 0.01-4.99 μm. In some embodiments, the thinningprocess removes the first substrate 402 and reduces the thickness of theinsulating layer 404 from an initial range of about 0.3-5 μm down to afinal range of about 0.01-1 μm.

In some embodiments, the thinning process reduces the first substrate402 (e.g., silicon wafer) thickness from an initial range about 400-700μm down to a final range of about 150-250 μm. In some embodiments, thethinning process reduces the first substrate 402 (e.g., silicon wafer)thickness from an initial range about 400-700 μm range down to a finalrange of about 100-150 μm. In some embodiments, the thinning processreduces the first substrate 402 (e.g., silicon wafer) thickness of aninitial about 400-700 μm range down to a final range less than about 100μm.

Referring to FIG. 3, method 300 proceeds to step 310, in which aconductive wiring layer is formed on the exposed insulating layer. Asillustrated in FIG. 8, a conductive layer is disposed on the backside409 the insulating layer 404 and patterned through photolithography andetching to form a conductive wiring layer 826. In some embodiments, theconductive wiring layer 826 can form an electrical connection with thesemiconductor device layer 608, the first conductive layer 610, and/orthe second substrate 716. The conductive wiring layer 826 can bepatterned based on the layout of the internal structure of memory arraydevice and/or the peripheral device structure, so that suitableinterconnect structures can be formed. In some embodiments, a wiringpattern is formed by etching the conductive wiring layer. In someembodiments, the wiring pattern is electrically connected to theplurality of conductive contacts. The conductive wiring layer 826 caninclude, but not limited to, W, Co, Cu, Al, Ag, Sn, metal silicides, orany other suitable materials. In some embodiments, the conductive wiringlayer 826 can include Cu, Ag, Al, Sn, W, or a combination thereof. Insome embodiments, the conductive wiring layer 826 are in or on one ormore back-end-of-line (BEOL) interconnect layers (not shown) at thebackside of the semiconductor structure 620.

In some embodiments, to reduce stress caused by the conductive wiringlayer 826, the distance in the vertical direction between the conductivewiring layer 826 and the semiconductor device layer 608 is about 3 μm.In some embodiments, the vertical distance between the conductive wiringlayer 826 and the semiconductor device layer 608 is between about 3 μmand 10 μm (e.g., about 3 μm, about 4 μm, about 5 μm, about 6 μm, about 7μm, about 8 μm, about 9 μm, about 10 μm, in any range bounded on thelower end defined by any of these values, or in any range defined by anytwo of these values). In some embodiments, the conductive wiring layer826 can completely overlap the semiconductor structure 620. In someembodiments, the conductive wiring layer 826 can partially overlap thesemiconductor structure 620. In some embodiments, the conductive wiringlayer is electrically connected to the first conductive layer. In someembodiments, the conductive wiring layer is electrically isolated fromthe first substrate.

Referring to FIG. 3, method 300 proceeds to step 312, in which apassivation layer is formed over the conductive wiring layer and theexposed insulating layer. As illustrated in FIG. 9, the passivationlayer 928 is formed over the backside 409 of the insulating layer 404and the conductive wiring layer 826. The dielectric material of thepassivation layer 928 can include oxides, nitrides, oxynitrides, or acombination thereof In some embodiments, the passivation layer 928includes silicon oxide, silicon nitride, silicon oxynitride, or acombination thereof. The passivation layer 928 can be formed by one ormore thin film deposition methods, such as ALD, CVD, PVD, or acombination thereof, lithography and etching. In some embodiment, theforming of the passivation layer 928 further comprises CMP to planarizeor flatten a surface of the passivation layer 928. In some embodiment,the passivation layer 928 is formed via CVD wherein the CVD is performedat deposition pressure of 1600-1700 mtorr, NH3 gas flow and/or oxygengas flow of 5000-8000 sccm, SiH₄ flow of 800-1150 sccm, RF power of5500-7500 watt, and deposition temperature of 450-500° C. In someembodiments, the thickness of the passivation layer is between about 0.3μm and 5 μm. In some embodiments, the thickness of the passivation layeris between about 0.3 μm and 1 μm. In some embodiments, the thickness ofthe passivation layer is about 1 μm. The passivation layer 928 can befurther patterned via lithography and etching based on the layout of theinternal structure of memory array device and/or the peripheral devicestructure, so that suitable interconnect structures can be formed.

In some embodiments, the 3D memory device can further include aperipheral device structure (not shown) on the second substrate 716,which are positioned face to face with their front sides facing towardsthe memory array structure. The peripheral device can include anysuitable digital, analog, and/or mixed-signal peripheral circuits usedfor facilitating the step of 3D memory device. For example, theperipheral device can include one or more of a page buffer, a decoder(e.g., a row decoder and a column decoder), a driver, a charge pump, acurrent or voltage reference, or any active or passive components of thecircuits (e.g., transistors, diodes, resistors, or capacitors). In someembodiments, the peripheral device is formed using CMOS technology.

In some embodiments, a 3D integrated wiring structure of a semiconductordevice is provided, wherein the structure is made by the methodsdescribed in any one of the above embodiments. In some embodiments, thesemiconductor device is a 3D memory device. In some embodiments, the 3Dmemory structure comprises a memory device layer having a plurality ofconductive contacts, and a first conductive layer. In some embodiments,the plurality of conductive contacts connects to the insulating layer atone end and connects to the first conductive layer at the other end.

Various embodiments in accordance with the present disclosure provide amethod for forming a 3D integration wiring structure and a semiconductordevice with an interconnect structure. The method for forming a 3Dintegrated wiring structure disclosed herein can include forming aninsulating layer on a front side of a first substrate; forming asemiconductor layer on a front side of the insulating layer; patterningthe semiconductor layer to expose at least a portion of a surface of theinsulating layer; forming a plurality of semiconductor structures overthe front side of the first substrate, wherein the semiconductorstructures include a plurality of conductive contacts and a firstconductive layer; joining a second substrate with the semiconductorstructures; performing a thinning process on a backside of the firstsubstrate to expose the insulating layer and one end of the plurality ofconductive contacts; and forming a conductive wiring layer on theexposed insulating layer. As a result, the method for forming a 3Dintegrated wiring structure disclosed herein can provide an interconnectstructure and enable wiring through a thick semiconductor device layer.

In some embodiments, a method for forming a 3D integrated wiringstructure is disclosed. An insulating layer is formed on a front side ofa first substrate. A semiconductor layer is formed on a front side ofthe insulating layer and patterned to expose at least a portion of asurface of the insulating layer. A plurality of semiconductorstructures, including a plurality of conductive contacts and a firstconductive layer, is formed over the front side of the first substrate.A second substrate is joined with the semiconductor structures followedby a thinning process on a backside of the first substrate to expose theinsulating layer and one end of the plurality of conductive contacts. Aconductive wiring layer is formed on the exposed insulating layer. Insome embodiments, the semiconductor structure is a 3D memory structure.

In some embodiments, a 3D integrated wiring structure is disclosed. The3D integrated wiring structure can include: an insulating layer; apatterned semiconductor layer disposed on a front side of the insulatinglayer; a plurality of semiconductor structures formed on at least aportion of the patterned semiconductor layer and the insulating layer,and a conductive wiring layer disposed on a backside of the insulatinglayer. In some embodiments, the structure further includes a firstsubstrate on the backside of the insulating layer. In some embodiments,at least a portion of the first substrate includes a reduced thicknessor is removed and at least a portion of the backside of the insulatinglayer is exposed. In some embodiments, the plurality of semiconductorstructures includes a plurality of conductive contacts and a firstconductive layer. In some embodiments, the semiconductor structure is a3D memory structure.

The foregoing description of the specific embodiments will so fullyreveal the general nature of the present disclosure that others can, byapplying knowledge within the skill of the art, readily modify and/oradapt for various applications such specific embodiments, without undueexperimentation, without departing from the general concept of thepresent disclosure. Therefore, such adaptations and modifications areintended to be within the meaning and range of equivalents of thedisclosed embodiments, based on the teaching and guidance presentedherein. It is to be understood that the phraseology or terminologyherein is for the purpose of description and not of limitation, suchthat the terminology or phraseology of the present specification is tobe interpreted by the skilled artisan in light of the teachings andguidance.

Embodiments of the present disclosure have been described above with theaid of functional building blocks illustrating the implementation ofspecified functions and relationships thereof. The boundaries of thesefunctional building blocks have been arbitrarily defined herein for theconvenience of the description. Alternate boundaries can be defined solong as the specified functions and relationships thereof areappropriately performed.

The Summary and Abstract sections may set forth one or more but not allexemplary embodiments of the present disclosure as contemplated by theinventor(s), and thus, are not intended to limit the present disclosureand the appended claims in any way.

The breadth and scope of the present disclosure should not be limited byany of the above-described exemplary embodiments, but should be definedonly in accordance with the following claims and their equivalents.

What is claimed is:
 1. A semiconductor device, comprising: an insulatinglayer; a semiconductor structure, wherein: the semiconductor structurecomprises a conductive contact and a first conductive layer; a frontside of the semiconductor structure is bonded with a substrate; and abackside of the semiconductor structure is disposed on a front side ofthe insulating layer; and a conductive wiring layer disposed on abackside of the insulating layer, wherein: the conductive contact isconnected to the conductive wiring layer at a first end; and theconductive contact is connected to the first conductive layer at asecond end that is opposite to the first end.
 2. The semiconductordevice of claim 1, further comprising: a patterned semiconductor layerdisposed on the front side of the insulating layer.
 3. The semiconductordevice of claim 2, wherein the patterned semiconductor layer comprisessingle crystalline silicon, or polycrystalline silicon.
 4. Thesemiconductor device of claim 2, wherein the patterned semiconductorlayer comprises a thickness in a range between 0.03 μm and 1 μm.
 5. Thesemiconductor device of claim 1, wherein the conductive contact andconductive wiring layer comprise copper, silver, aluminum, tin,tungsten, or a combination thereof
 6. The semiconductor device of claim1, wherein the semiconductor structure further comprises a memory array.7. The semiconductor device of claim 6, wherein the memory arraycomprises a memory device layer having a plurality of memory cells. 8.The semiconductor device of claim 7, wherein the memory device layercomprises an alternating conductor/dielectric stack, comprisingalternating conductor layers and dielectric layers.
 9. The semiconductordevice of claim 8, wherein the conductor layers comprise metal andpolysilicon.
 10. The semiconductor device of claim 8, wherein thedielectric layers comprise silicon oxide and silicon nitride.
 11. Thesemiconductor device of claim 7, wherein the memory device layercomprises a thickness between about 1 μm and 50 μm.
 12. Thesemiconductor device of claim 7, wherein the memory device layer furthercomprises a NAND string extending through the alternatingconductor/dielectric stack.
 13. The semiconductor device of claim 12,wherein the NAND string comprises the plurality of memory cellsvertically stacked.
 14. The semiconductor device of claim 6, furthercomprising: a peripheral device structure on the substrate, wherein theperipheral device structure is bonded to the memory array.
 15. Thesemiconductor device of claim 14, wherein the peripheral devicestructure comprises a peripheral device, the peripheral devicecomprising a CMOS device.
 16. The semiconductor device of claim 14,wherein the conductive wiring layer is electrically connected to theperipheral device structure.
 17. The semiconductor device of claim 14,wherein the peripheral device structure and the memory array aredisposed face to face with each other and are disposed over the frontside of the insulting layer.
 18. The semiconductor device of claim 1,wherein the conductive contact extends through the insulating layer. 19.The semiconductor device of claim 1, wherein the conductive contactcomprises a diameter between about 0.3 μm and 5 μm.
 20. Thesemiconductor device of claim 1, wherein the insulating layer comprisesa thickness in a range between about 0.3 μm and 5 μm.